@Armus: maybe you can stop calling it multiboxing and start calling it client modification. People obviously get confused by the terminology.
As has been stated by AndyB before, FC does not consider multiboxing a problem.
The problem here is people using tools that change the way the game client works, allowing them to control characters in a way that is not possible by playing the game normally (i.e. movement synchronisation and other things mentioned in the original post).